The email goes on to encourage supporters to donate to the president's campaign for a chance to visit Chicago and attend the fundraiser.

Obama has frequently mentioned his admittance to the "gray hair club." At a Democratic National Committee fundraiser last year, the president repeatedly referenced his changing appearance.

"Some of you have noted that I’ve now turned 50. And these are dog years that presidents live, so the gray hairs are accelerating much more rapidly than I anticipated,” Obama quipped.